In Photon Pile-up you get extra points for piling up three touching ultraviolet photons. These are colored purple in the game. You get fewer points for piling three touching photons of other single colors. But don't let the photons pile up too high! Keep the GALEX "telescope" spinning.

When you finish this game, you can post your game results on Facebook. Challenge your friends!

You probably know from other pages on The Space Place, that light also acts like waves. You might want to pay another visit to the Land of the Magic Windows or go again to play in the light waves on "What is a laser?"

Of the kinds of light in the Photon Pile-up game, microwaves are the longest waves and X-rays are the shortest waves.

A very special telescope

Our eyes are lousy at detecting any kind of photons except visible light photons. Thank goodness we have telescopes like GALEX.

This GALEX image in ultraviolet light shows beautiful spiral galaxy M81. M81 is about the same size and brightness as our own Milky Way Galaxy.

GALEX can see, for example, that new stars are forming in a particular region of space. It can see things like the strange, long tail of the star Mira, invisible before astronomers discovered it in a GALEX image.

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A very special telescope

Our eyes are lousy at detecting any kind of photons except visible light photons. Thank goodness we have telescopes like GALEX.

This GALEX image in ultraviolet light shows beautiful spiral galaxy M81. M81 is about the same size and brightness as our own Milky Way Galaxy.

GALEX can see, for example, that new stars are forming in a particular region of space. It can see things like the strange, long tail of the star Mira, invisible before astronomers discovered it in a GALEX image.